Heat-treating furnace



Oct. 28, 1952 ps 2,615,701

HEAT-TREATING FURNACE Filed 00?. 6, 1949 2 SHEETS-SHEET 2 (ATTORNGLY/ Patented Oct. 28, 1952 UNITED STATES OFF ICE nm'rrram'rme runnnon Harold N. Ipsen, ;Rockford,' Application October 6, 1a49, ,s ria11no.'11am This invention relates to a heat treating fur-- nace, and has more par'ticular reference toa furnace of the type in which articles to be treated are heated in a neutral atmosphere while supported on a horizontally movable conveyor and maintained in the atmosphere until the time of their delivery'downwardly into a quenching liquid.

One object of the present invention is to avoid objectionable cooling of the heated articles during their transfer to the quenching tank from the chamber in which they are heated.

A more detailed object is to transfer the heated articles .to the quenching tank by means of a flexible conveyor movable along .a :novel support,

all parts of whichwill stand the maximum heating temperature without interfering with the movement of the conveyor.

The invention also resides in the novel construction of the eonveyorsupport Wh'ih facilitates sliding of the conveyor while in a bent condition.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a vertical sectional view taken longitudinally through a heat treating apparatus embodying the present invention.

Fig. 2 is a fragmentary sectional view taken along the line 2 -2 of Fig. 1.

Fig. 3 is a view similar to Fig. 1 showing a modified arrangement of the muflle heater.

Fig. 4 is a sectional view taken along the line 44 of Fig. 3.

While the invention is applicable to furnaces of the so-called continuous type, it is shown in the drawings for purposes of illustration embodied in a batch type furnace comprising a mufile I defined by top, side, bottom, and rear walls H to M which are surrounded by a chamber through which heated gases may rise to heat the muille and escape through an opening 16 in the top of the furnace. workpieces are loaded into the mufile through an opening in a front brick wall I! which opening is normally closed by a door 48.

The floor [3 of the muffle comprises a layer or plate of suitable heat resistant material capable of readily conducting heat delivered to a chamber I!) which is disposed below the floor plate is and above a brickwork base 20. Crossbars 2| resting on the base support the plate [3 in horizontal position. At its forward end, the floor plate I3 is connected to an extension 22 of similar material curving downwardly into a "w'zerticalplane and cooperating with "the rear surfaceof the fumace'wall l'l to form a vertical opening 23 through which the heat treated parts may be dischargeddownwardly into quenching liquid =24 in a'tank disposed below the furnace. The-extension'i-Z defines the front wall of the heating chamber "I9, and its corner surface 25 is of gradually rounded contour.-

between the'supporting bars 2| 'or between these bars and "one end of theheating chamber [9. Inthe construction shown in Fig. 1-, one of the burners is disposed between the rear bar 2| and the rear end wall of the chamber I9 while in-the form shown in Fig. 3, one of the'burners is located between the front cross'member .2!

and the curved extension 22 of the furnace .floor. -Wi=th 'both of these arrangements, the entire floor I3 ofthe-furnace and the extension 22'are exposed substantially directly to the burner heat and become heated to a substantially uniform temperature.

While being heated in the mufile ID, the work is supported from the hearth or floor [3 through the medium of a. flexible tray or carrier 21 which is slidably movable along the furnace floor and is adapted to bend downwardly into the discharge passage 23 so that the workpieces spread along the carrier will be delivered into the passage in a substantially continuous stream as the carrier advances. The carrier is built up of plate-like links 28 of heat resistant alloy arranged end to end and side by side so as to form a substantially flat upper surface. Each link has depending side flanges pivotally connected together by pins 29 which may carry rollers 30 which rest on the floor surface and facilitate sliding of the conveyor along the latter and downwardly around the curve 25.

The carrier 21 is of a width substantially equal to the muffle floor l3, and, when in the normal position shown in Figs. 1 and 3, extends from the rear muffle wall 14 forwardly and substantially to the discharge passage 23. A crossbar 3| extends across the rearmost row of the links 28' and is secured thereto to constitute a rear wall for retaining the workpieces on the carrier.

Movement of the carrier 21 forwardly to discharge the parts thereonlnto the passage 23 or reversely to withdraw the carrier from the passage and reposition it on the furnace floor l3 for receiving the next batch of parts is effected by two relatively narrow chains 32 laterally spaced apart and connected at opposite ends to the leading and trailing ends of the carrier. Each chain extends from the leading end of the carrier downwardly around the curved surface 25 and along the rear wall of the discharge passage 20, then horizontally and rearwardly through a passage 33 beneath the base 20, then upwardly behind the rear furnace wall around sprockets 34 and 35, and finally through a horizontal hole 36 in the furnace wall and the rear end wall [4 of the muille. The sprockets are fast on shafts journaled at opposite ends in a suitable framework, and one of them is adapted to be turned by hand or a suitable power actuator.

By turning the sprocket 34 counterclockwise as viewed in Fig. 1, it will be apparent that a. pull will be exerted on the leading end of the carrier I claim as my invention:

In a heat treating furnace, the combination of, a generally horizontal base. a rigid floor plate of heat resistant material spaced above said base and cooperating with the latter to form a heat generating chamber, an extension of said plate curving downwardly from one end thereof to said base and forming an upright wall closing one end of said chamber, means enclosing said floor plate andisaid wall to define a muille above the floor and an'upright material discharge opening at the end thereof, a heater disposed in said chamber immediately adjacent said curved extension and the adjacent portion of said floor plate and operable to radiate heat directly to the inner surfaces of the plate and extension and thereby heat the same and the material uniformly 21 to shift the latter forwardly and bend it downwardly into the passage 23. In the reverse rotation of the sprocket, the pull will be exerted on the rear end of the carrier to draw it back into normal position on the furnace floor. By virtue of the gradual curving of the surface 25 at the forward end of the muille floor, sharp bending of the carrier 21 is avoided so that the latter will slide readily along the floor and then downwardly into the discharge passage 23. The corner 31 between the passages 23 and 33 is similarly rounded. With surfaces of such rounded contour, the carrier will slide freely, and the necessity of using sprockets or other bearings in the portions of the furnace which become heated to a substantial temperature is avoided. At the same time, the surface 25 and, in fact, all portions of the floor extension 22 may be held at the furnace temperature as a result of which there is no cooling of the workpieces during their transfer from the muflle into the discharge passage 23. As a result, better control of the hardening process is achieved.

This application is a continuation-in-part of my co-pending application Serial No. 651,763, filed March 4, 1946, later abandoned.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,333,371 Barnhart Mar. 9, 1920 1,493,758 Lamie May 13, 1924 1,690,231 Klugh Nov. 6, 1928 2,109,081 Bowman Feb. 22, 1938 Ness Feb. 5, 1946 

